[Clinical evaluation of a novel HBsAg quantitative assay].

The clinical implication of the hepatitis B surface antigen (HBsAg) concentrations in HBV-infected individuals remains unclear. The aim of this study was to evaluate a novel fully automated Chemiluminescence Enzyme Immunoassay (Sysmex HBsAg quantitative assay) by comparative measurements of the reference serum samples versus two independent commercial assays (Lumipulse f or Architect HBsAg QT). Furthermore, clinical usefulness was assessed for monitoring of the serum HBsAg levels during antiviral therapy. A dilution test using 5 reference-serum samples showed linear correlation curve in range from 0.03 to 2,360 IU/ml. The HBsAg was measured in total of 400 serum samples and 99.8% had consistent results between Sysmex and Lumipulse f. Additionally, a positive linear correlation was observed between Sysmex and Architect. To compare the Architect and Sysmex, both methods were applied to quantify the HBsAg in serum samples with different HBV genotypes/subgenotypes, as well as in serum contained HBV vaccine escape mutants (126S, 145R). Correlation between the methods was observed in results for escape mutants and common genotypes (A, B, C) in Japan. Observed during lamivudine therapy, an increase in HBsAg and HBV DNA concentrations preceded the aminotransferase (ALT) elevation associated with drug-resistant HBV variant emergence (breakthrough hepatitis). In conclusion, reliability of the Sysmex HBsAg quantitative assay was confirmed for all HBV genetic variants common in Japan. Monitoring of serum HBsAg concentrations in addition to HBV DNA quantification, is helpful in evaluation of the response to lamivudine treatment and diagnosis of the breakthrough hepatitis.

[False positive serum des-gamma-carboxy prothrombin after resection of hepatocellular carcinoma].

Measurements of serum concentrations of des-gamma-carboxy-prothrombin (PIVKA-II) are widely used for diagnosing hepatocellular carcinoma (HCC). Recently, when we evaluated the correlation of PIVKA-II between two commercially available PIVKA-II immunoassay kits (Lumipulse f vs. Picolumi) to introduce it in our hospital, false high values of PIVKA-II were observed in Lumipulse assay. Four(4%) of 100 serum samples showed false high values, and all of them were obtained from patients less than 2 month after curative resection of HCC. Examining additional 7 patients with HCC resection, serum samples from the 5 patients had the same trend. To elucidate the non-specific reaction by Lumipulse assay which utilized alkaline phosphatase (ALP) enzymatic reaction, inhibition assays by various absorbents such as inactive ALP and IgM antibodies were performed. Excess of inactive ALP reduced the high values of PIVKA-II. Note that anti-bleeding sheets (fibrinogen combined drug), which included bovine thrombin, were directly attached on liver of all patients with HCC resection in this study. As the sheets also contaminate ALP and probably produce IgM antibodies to ALP, the IgM may cross-react with anti-PIVKA-II antibodies directly. Taken together, it was suggested that produced antibodies against ALP derived from anti-bleeding sheets led false high values of PIVKA-II in the patients with HCC resection.

[Fundamental and clinical evaluation of hepatitis B virus core-related antigen assay by LUMIPULSE f].

A sensitive chemiluminescence enzyme immunoassay (CLEIA) has been developed for hepatitis B virus (HBV) core-related antigens (HBcrAg) detection. The HBcrAg is designated as the precore/core gene products including HBeAg. The aim of this study is to evaluate reproducibility of HBcrAg and correlation with HBV-DNA in serum using the automatic LUMIPULSE f to estimate an assay suitable for general laboratory use. In this study, we demonstrated that HBcrAg assay had highly intra-assay reproducible [coefficients of variation(CVs); 2.8-5.2%] and inter-assay reproducible [CVs; 3.9-9.1%]. When the cutoff value was tentatively set at 1 kU/ml, all healthy controls (HBsAg/HBV-DNA negative; n=100) and anti-HCV antibody-positive (n=50) sera were identified as negative. The assay showed a detection limit of 0.5 kU/ml using four serially diluted HBV high-titer sera, indicating higher sensitivity than HBV-DNA (transcription-mediated amplification). The HBcrAg concentration correlated positively with serum HBV-DNA (n=125, r = 0.860, p < 0.0001) regardless of HBeAg, although the HBcrAg levels were higher in HBeAg-positive group than in HBeAg-negative group. In the natural course of HBV infection, the HBcrAg concentration usually changed in accordance with HBV-DNA levels, however during lamivudine therapy the change of HBcrAg was more gradual than that of HBV-DNA. In conclusion, HBcrAg concentration provides a reflection of HBV virus load equivalent to HBV-DNA level, and the assay therefore offers a simple method for monitoring hepatitis B patients.